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pg_ctl is supposed to daemonize the postmaster process, so that it's not affected by signals to the launching process group. Before this patch, if you had a shell script that used "pg_ctl start", and you interrupted the shell script after postmaster had been launched, postmaster was also killed. To fix, call setsid() after forking the postmaster process. Long time ago, we had a 'silent_mode' option, which daemonized the postmaster process by calling setsid(), but that was removed back in 2011 (commit f7ea6beaf4). We discussed bringing that back in some form, but pg_ctl is the documented way of launching postmaster to the background, so putting the setsid() call in pg_ctl itself seems appropriate. Just putting postmaster in a separate session would change the behavior when you interrupt "pg_ctl -w start", e.g. with CTRL-C, while it's waiting for postmaster to start. The historical behavior has been that interrupting pg_ctl aborts the server launch, which is handy if the server is stuck in recovery, for example, and won't fully start up. To keep that behavior, install a signal handler in pg_ctl, to explicitly kill postmaster, if pg_ctl is interrupted while it's waiting for the server to start up. This isn't 100% watertight, there is a small window after forking the postmaster process, where the signal handler doesn't know the postmaster's PID yet, but seems good enough. Arguably this is a long-standing bug, but I refrained from back-batching, out of fear of breaking someone's scripts that depended on the old behavior. Reviewed by Tom Lane. Report and original patch by Paul Guo, with feedback from Michael Paquier. Discussion: https://www.postgresql.org/message-id/CAEET0ZH5Bf7dhZB3mYy8zZQttJrdZg_0Wwaj0o1PuuBny1JkEw%40mail.gmail.com
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.